Resin recycling system

ABSTRACT

A system for recycling reusable resin mold products recovered from discarded apparatuses is disclosed. This recycling system includes a crushing system for crushing resin mold products one kind by one kind into crushed resinous pieces and packing the same in a bag, a classification system for irradiating a light beam to the resin in the bag and classifying the bags into respective kinds of resins based on a reflected beam therefrom, a cleaning system for separately cleaning the respective kind of crushed resinous pieces taken out of the bag to remove foreign matters adhered onto the surfaces of the crushed resinous pieces therefrom, and a recovery system for recovering the cleaned crushed resinous pieces.

[0001] This application is based on Patent Application Nos. 2000-256202filed Aug. 25, 2000 in Japan and 2001-047750 filed Feb. 23, 2001 thecontent of which is incorporated hereinto by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a system for recycling resinousmaterials from resin mold products recovered from discarded apparatuses(such as home electric appliances, electronic devices or cars), moreparticularly to a crushing system for crushing polymer parts obtained bydisassembling the recovered products to reduce the volume thereof; aclassifying system for classifying the resinous materials into theirkinds, preferably into kinds of fire retardants added thereto; and acleaning system for removing foreign matters such as coated films,labels or seals applied to the products or other contamination thereof.

[0004] 2. Description of the Related Art

[0005] Plastics light in weight and excellent in mechanical strengthhave often been used for home electric appliances, OA apparatuses,communication apparatuses or others as internal parts or externalcasings thereof. From a point of view of the environmental protection,the conversion from a mass-production/mass-scrap economy in the past toa circulation type economy is required. In such a recent trend, afull-scale recycle of resinous products has been urgently demanded; forexample, the recycling of home electric appliances has been obligated bylaw. However, regarding the material recycle in which the resin moldproducts are recovered and reused as resinous materials, it is donesolely in a case wherein it is possible to specify to some extent whatkind of resin is used, because there is a problem peculiar to the resinin that if different kinds of resins are mixed together, functionsinherent to the resin are significantly damaged. Accordingly, a resinrecycling system is desired, which is capable of correctly classifyingvarious kinds of resinous products used in the discarded appliances orapparatuses and regenerating the same as fresh resinous materials forthe home electric appliances, OA apparatuses or communicationapparatuses.

[0006] To proceed a high-quality recycling, it is necessary to correctlyidentify and classify materials of resin mold products containingvarious kinds of additives including fire retardant. Regarding theidentification of materials of the resin mold products, ahigh-performance resin identification device has recently beendeveloped, and is becoming reality. This device, however, necessitates aconsiderable care on the operation, maintenance and inspection thereofas well as it is expensive in cost. The most effective method foridentifying materials of the resin mold products solely from a point ofview of the material identification is to provide such a resinidentification device in each of the disassembly factories. This methodis, however, problematic from the economical view point or a view pointof stable operation of the system.

[0007] To operate the above-mentioned resin identification device underthe stably controlled condition, it is desirable to provide thedisassembly factory for recovering the resin mold products at a positiondifferent from that of the resin identification device. In such a case,it is necessary to convey the resin mold products from the disassemblyfactory to the position at which the resin identification device isprovided.

[0008] However, the resin mold products obtained from the discardedapparatuses have various shapes and sizes distributed from a small oneto an extremely large one. Therefore, if they are packed into a box or abag while maintaining their shapes, the physical transportation costbecomes wasteful since a bulk specific weight is very small to reduce aweight relative to a volume thereof. Accordingly, it is desired to crushthe resin mold products into pieces having an economically preferablesize (a size capable of achieving a proper transportation efficiency).As a crusher used for this purpose, it is possible to use a commerciallyavailable crusher such as a hammer mill, a cutter mill, a two-axiscrusher and the like which is capable of crushing the resin moldproducts into pieces having about 50 mm or less in size.

[0009] However, the resin mold products recovered from disassemblingappliances have various sizes as set forth above. In order to load allof the resin mold products and crush them into pieces having about 50 mmor less in size, it becomes necessary to provide a very big crusherhaving a loading opening. Since these equipment is costly, there is aproblem that it is economically impossible to install such expensiveequipment at each of small factories.

[0010] Further, if the resin mold products are crushed altogether bysuch means, however, many of the resin mold products formed of differentkinds of resins are crushed in a mixed state, and, as a result, it isnecessary to identify crushed pieces in which many kinds of resins existusing an identification apparatus. Although such identification ispossible in principle, industrialization thereof is difficult inpractice because it is necessary to respectively identify kinds ofresins of a large number of crushed pieces and classify the same intothe respective materials after the identification.

[0011] In addition, to economically realize the material recycling ofhigh-quality resinous materials, it is necessary to classify kinds ofresins containing various additives such as fire retardant at a highaccuracy and a high speed. As a method for classifying the kinds ofresins, a technique using, for example, a near infrared ray absorptionhas been known and various devices are marketed. However, this methodhardly identifies kinds of resins with many identification errors and isunsuitable for the high accuracy and high speed identification. Anothermethod utilizing intermediate infrared absorption has been also known.Although this method is capable of identifying not only kinds of resinsbut also those of additives such as fire-retardant at a high accuracy,there is a problem in that a long time is required for theidentification and therefore unsuitable for a high speed processing.

[0012] On the other hand, the recovered resinous products may be coatedwith films, applied with labels or the like or carry variouscontaminants, which are liable to enter the resin during the treatmentof the resinous products to result in a problem to significantlydeteriorate the characteristic of the resin to be reused.

[0013] Although various trials have been attempted for removing foreignmatters carried on the surface of the resinous product, for example, bya mechanical method and the separation or removal with a solvent, thereis a problem in either cases. For instance, if the removal of the coatedfilm or the label is intended by using a crusher such as a ball mill,the resin is softened due to heat generated by the friction during thecrushing operation, which disturbs the resin removal or causes there-adhesion of the foreign matters once removed. Also, there is anothermethod wherein the foreign matters are dissolved with a solvent and thenseparated and removed from the resin. This method, however, has aserious problems in that the used solvent must be regenerated ordiscarded, and also has other problems in that an apparatus usedtherefor is complicated in structure and unfavorable from the economicalpoint of view.

[0014] There is a still further method for removing the coated film orlabels, called as a dry blast treatment, wherein an abrasive materialsuch as sands or metallic particles is used for scraping off the foreignmatters from the surface of the resinous product. According to thismethod, however, particles of the abrasive material may stick into thesurface of the resinous product and remain as they are as new foreignmatters. Also, the resin may be softened by heat generated due to thefriction of the abrasive material and cause the re-adhesion of theforeign matters once removed.

SUMMARY OF THE INVENTION

[0015] The present invention has been done to solve the above-mentionedproblems, and an object of the present invention is to provide a resinrecycling system for crushing resin mold products collected fromdiscarded apparatuses into crushed resinous pieces to reduce an apparentvolume thereof, without identifying that the resin mold product belongsto what kind of resin but with taking care that a plurality of kinds ofresins are not mixed with each other; identifying a kind of the crushedresinous pieces to classify the same to that kind for easily determininga field in which the same is reused; and removing foreign matters fromthe surface of the classified crushed resinous piece to be reusable asresinous material.

[0016] Another object of the present invention is to provide a crushingsystem for roughly crushing polymer parts (including a large-sized ones)taken out from the collected and disassembled apparatuses to reduce anapparent volume thereof.

[0017] A further object of the present invention is to provide anidentification system for effectively identifying a kind of crushedresinous pieces obtained by crushing resin mold products collected fromdiscarded electric or electronic equipment without identifying that theresin mold product belongs to what kind of resin but with taking carethat a plurality of kinds of resins are not mixed with each other.

[0018] Further, the present invention is to solve the above-mentionedproblems of the prior art by providing a cleaning system forthermoplastic resin products wherein, when the resin products arecollected and cleaned to be reusable resinous material, foreign matterssuch as coated films or labels adhered on the surface of the resinproducts are sufficiently removed therefrom so that the resinousmaterial is usable in the same field as before.

[0019] To achieve the above objects, according to one aspect of thepresent invention, a resin recycling system is provided, which comprisescrushing means for individually crushing resin mold products intocrushed resinous pieces in which 70% or more of the crushed resinouspieces have an equivalent diameter in a range from 1 to 50 mm, packingmeans for packing the crushed resinous pieces of the respective moldproduct into a bag having a transparent portion, classification meansfor irradiating a light beam to the crushed resinous pieces in the bagthrough the transparent portion, identifying a kind of the crushedresinous pieces based on a reflected beam therefrom, and classifying thebags into respective kinds of resins, and cleaning means for taking thecrushed resinous pieces out from the bag and cleaning the crushedresinous pieces of the respective kind to remove foreign matters adheredon the surface thereof.

[0020] In the above description, the term, “equivalent diameter” is adiameter of a circle having the same area as that of a projected area ofan object.

[0021] Here, the equivalent diameter of the crushed resinous piece ispreferably in a range from 3 to 40 mm, more preferably from 5 to 30 mm.A ratio of the crushed resinous pieces having the equivalent diameterwithin these ranges is preferably 80% or more, more preferably 90% ormore.

[0022] If the equivalent diameter of the crushed resinous piece issmaller than 1 mm, there is an inconvenience in that foreign matterscould not be removed during cleaning by the cleaning means, because thecrushed resinous piece is pulverized. For example, when the cleaning iscarried out by the abrasion, the abrasion becomes impossible. Also, thesmall resinous pieces are liable to stick to the interior of the crusheror the bag due to static electricity.

[0023] On the other hand, if the equivalent diameter of the crushedresinous piece exceeds 50 mm, the crushed resinous pieces may be stillthree-dimensional to obstruct the sufficient volume reduction.

[0024] The crushing may be carried out at one step. However, if the moldproduct is too large in size to be introduced into an ordinary crusher,the crushing may be carried out at two steps wherein the mold product isroughly crushed by a rough crusher and then introduced into the ordinarycrusher.

[0025] Since one resin mold product is formed of one kind of resin, itis possible to effectively reduce the apparent volume of the resin moldproduct while preventing the finely crushed resinous pieces from mixingwith other kinds by crushing the resin mold product separately one kindby one kind and immediately packing into a bag. By crushing the resinmold product one by one which is recovered from the discarded apparatusin the manual disassembly factory and packing the crushed resinouspieces in a bag, the conveying efficiency is enhanced Since the crushedresinous pieces in the bag is of the same kind of resin, it is possibleto carry out the economical classification by classifying the bags.

[0026] In this regard, to further enhance the working efficiency, whenit is apparent in advance that the mold products are formed of the samekind of resin, they are crushed together and packed in one bag. Forexample, if there are plurality of mold members of the same shape andfunction (such as paper feeding trays of different sizes of a copyingmachine) and it is confirmed that they are formed of the same kind ofresin, they may be crushed together and packed in one bag. This methodis favorable for facilitating the working efficiency when there are anumber of small resinous members of a similar shape and the same kind ofresin in one discarded apparatus.

[0027] The transparent portion of the bag is necessary for the purposeof preventing the light beam irradiated to the crushed resinousparticles or reflected therefrom from being adversely effected by thepassage thereof through the bag. Accordingly, if the adverse effect onthe detection due to the passage of light beam through the bag isnegligible, the transparent portion is not necessarily completelytransparent. In short, it is sufficient that the bag is provided with alight-passing area (transparent portion) which does not adversely effectthe detection, and in this text, such a light-passing area is referredto as a transparent portion. The transparent portion may extendthroughout the bag. Such a bag may be formed, for example, ofpolyethylene. In this regard, a thickness of the transparent portion isgenerally 100 μm or less. Other materials may be used for this purpose,such as resinous film, resinous net or metallic net.

[0028] A method for identifying a kind of resin includes, for example,one based on a Raman spectrum analysis, wherein a Raman spectrumobtained from the reflected light beam from the resin to be inspected(i.e., the crushed resinous pieces in the bag) is sequentially comparedwith Raman spectra obtained from reflected light beams from variousknown resins prepared in advance to find whether or not there is thecoincidence between both the spectra. The method based on the Ramanspectrum analysis is favorable because it is less adversely effectedfrom color tone or surface contamination of the crushed resinous piece.One method for identifying kind of resin based on the Raman spectrumanalysis is disclosed, for example, in paragraphs from 0011 to 0018 ofJapanese Patent Application Laid-open No. 10-38807. Alternatively, aninfrared or near infrared spectrum analysis may be used for thispurpose.

[0029] One method for classifying the bags into kinds of resins includesthe steps of storing an identified kind of crushed resinous pieces andan expected arrival time at which the bag of the crushed resinous pieceswould reach a predetermined classification position on a conveying path,in correspondence to each other, and recovering the bag reaching theclassification position at the expected arrival time from the conveyingpath.

[0030] The predetermined classification position may be different inaccordance with kinds of resins. In such a case, the classified recoveryis carried out wherein, for example, the bag in which resin A is packedis recovered from the conveying path at the classification position forthe resin A, and the bag in which resin B is packed is recovered fromthe conveying path at the classification position for the resin B.

[0031] The predetermined position may be a specified one irrespective ofkinds of resins. In such a case, the classified recovery is carried outin such a manner that the bag of resin A (the resin A is packed)reaching the classification position is guided from the conveying pathto a collecting container or the like for the resin A, and similarly,the bag of resin B reaching the classification position is guided fromthe conveying path to a collecting container or the like for the resinB.

[0032] The expected arrival time is obtained by an identification time,a distance between an identification position and the classificationposition, and a conveying speed. While the expected arrival time may becalculated from these data every time, it may be determined as a time apredetermined period after an identification time, since the abovedistance and the conveying speed are constant.

[0033] The cleaning means removes foreign matters such as plated layers,coatings, labels or contaminants adhered to the surface of the crushedresinous piece therefrom.

[0034] The cleaning means may be a device having a cleaning vessel andan agitator member provided in the cleaning vessel wherein at least partof the inner wall of the cleaning vessel and/or a surface of theagitator member has an abrasive surface (roughened surface) for removing(scraping or scrubbing off) the foreign matters on the surface of thecrushed resinous piece. Water or an aqueous rinsing liquid may besupplied into the vessel to enhance the removal of foreign matters.

[0035] The abrasive surface (roughened surface) may be of any structure,provided it could sufficiently clean the surface of the crushed resinouspiece. The abrasive surface preferably has the irregularity having adepth in a range from 40 to 2000 μm. By the contact of crushed resinouspieces with this roughened surface having such irregularity, foreignmatters such as coated film or label adhered onto the surface of thecrushed resinous piece are sufficiently scrubbed or scraped off andremoved. If the depth of the irregularity is less than 40 μm, theforeign matters are not sufficiently removable. Contrarily, if exceeding2000 μm, the surface of the crushed resinous piece is excessivelyscraped off to lower the resin recovery percentage. The depth of theirregularity is preferably in a range from 50 to 1000 μm, morepreferably from 60 to 500 μm. If the depth is within such a range, theforeign matters are not excessively scraped off but sufficientlyremovable.

[0036] In the device for continuously cleaning the crushed resinouspieces, the crushed resinous pieces are continuously supplied from oneend of the cleaning vessel, conveyed in one direction within thecleaning vessel, for example, by a screw or others and continuouslycollected from the other end. If water or aqueous liquid is used in sucha device, the feeding of water or aqueous liquid is carried out in asimilar manner that the water or the aqueous liquid is also continuouslyfed from the one end and/or intermediate portions of the cleaningvessel, flows in the same direction in the cleaning vessel and iscontinuously drained from the other end.

[0037] When water or aqueous liquid is used during the cleaningoperation, it functions as a lubricant between the crushed resinouspieces and the irregularity to prevent the surface of the crushedresinous piece from being excessively scraped off as well as to suppressthe temperature rise of the crushed resinous piece due to the coolingoperation of water whereby the softening thereof is inhibited. Also, theforeign matters such as coated film or label once removed are quicklydischarged out of the cleaning device and do not adhere again to thecrushed resinous pieces.

[0038] The resin recycling system may have a recovery means forseparating foreign matters from a mixture of the crushed resinous piecescleaned by the cleaning means and the foreign matters and recover thecrushed resinous pieces. The crushed resinous pieces and the foreignmatters may be separated from each other, for example, by wind. Also,magnet force may be used for removing metallic material. When water oraqueous liquid is used for the cleaning operation, it is possible toremove foreign matters together with water or the like. In this regard,it may be so adapted that, after removing foreign matters from water oraqueous liquid through a filter or others, the water or aqueous liquidis reused.

[0039] The resin mold products which can be recycled after beingcrushed, classified and cleaned according to the present inventioninclude, for example, those used as housings or parts of variousapparatuses used in an OA and home electric appliance field, an electricand electronic field, a sanitary field, an automobile field or asundries field. For example, various resinous housings, trays orinternal resinous parts used in copying machines, printers, personalcomputers, TV sets, various monitors or mobile telephones.

[0040] The resinous material recycled according to the present inventionincludes, for example, various styrene type resins such asacrylonitrile-butadiene-styrene resin, polystyrene resin oracrylonitrile-styrene resin; polycarbonate resin; olefin type resin suchas polyethylene or polypropylene; polyamide type resin such as PA 6,PA66, PA46 or PA12; polyester type resin such as polybutyleneterephthalate, polyethylene terephthalate or polyacrylate; polyphenyleneether resin; polyacetal; polyvinylchcloride resin; polysulfon; PPS;polyether sulfon; ethylene-vinylacetate copolymer;ethylene-ethylacrylate copolymer; EVOH; polyamide type elastomer;polyester type elastomer; and alloys in which two or more of them aremixed. These are all identifiable by the classification means of theinventive system.

[0041] The classification means of the inventive system can identifyadditives contained in the crushed resinous pieces, such as variousfire-retardants including halogen type and phosphor type; variousfire-retardant assistants such as antimony trioxide, antimony tetroxide,antimony pentoxide, chlorinated polyethylene or tetrafluoroethylenepolymer; inorganic filler such as glass fiber, carbon fiber, metallicfiber or talc; anti-fungus agent, mildewcide, plasticizer, antistatic orsilicone oil. These additives are identifiable if a considerable amountof them is contained in the crushed resinous piece (resin mold product),for example, 1 part by weight or more, preferably 2 parts or more in 100parts by weight of the resin mold product.

[0042] To achieve the above objects, one aspect of the crushing systemaccording to the present invention comprises an endless conveyor forconveying polymer mold products, and an opposed member having an opposedsurface confronting at least one end of the endless conveyor on theconveying-directional side and disposed so that a distance between theopposed surface and a conveying surface of the endless conveyor becomessmaller in the conveying direction, wherein crushing edges or crushingpins are provided on at least one of the conveying surface of theendless conveyor and the opposed surface of the opposed member, todirect toward the other, whereby the polymer mold products transportedby the endless conveyor are pushed into a gap between the conveyor andthe opposed member and crushed with the crushing edges or pins.

[0043] The crushing edge or pin is a member having a function forcrushing the polymer mold product conveyed by the endless conveyor andpushed into a gap between the same and the opposed member. That is, eventhough shapes thereof are different from those generally thought fromthe feeling of words “edge or pin”, any member may be the crushing edgeor pin according to the present invention, if it is provided on at leastone of the conveying surface of the endless conveyor and the opposedsurface of the opposed member to direct toward the other, and has theabove-mentioned crushing function. The crushing edge or pin preferablyhas a sharp portion to be in contact with the polymer mold productbecause a larger crushing performance is exhibited thereby.

[0044] Preferably, the crushing edges or pins are provided on theconveying surface of the endless belt, and recesses or holes areprovided on the opposed surface of the opposed member for allowing tipends of the crushing edges or pins provided on the endless conveyor topass through the same.

[0045] The opposed member may be a second endless conveyor.

[0046] To achieve the above-mentioned objects, one aspect of theidentification system of the present invention is an identificationdevice for irradiating a light beam to a polymer products conveyed byconveyor means, detect the reflected beam or the dispersed beam from thepolymer product by a sensor element, and identify a kind of the polymerproduct based on the detected result, wherein the sensor element isdisposed at a predetermined position in the vicinity of a conveying pathof the polymer product, and a distance determination mechanism isdisposed in the conveying means or in the vicinity thereof, for opposingthe polymer product passing by the sensor element to the sensor elementat a distance between the both.

[0047] Selectable polymers include, for example, rubber-like polymer,thermoplastic elastomer and resin. Of them, resin is more preferable.Additives in the resinous material and the selectable polymeric materialare the same as described above.

[0048] The conveyor means may be an endless conveyor and the sensorelement may be disposed at a predetermined position beneath theconveying path constituted by the endless conveyor, and the distancedetermination mechanism may be a light window provided at each ofportions of the endless conveyor passing over the predeterminedposition.

[0049] According to this arrangement, the light beam is irradiated frombeneath to the polymer conveyed on the endless conveyor through thelight window, and the reflected or disperse light beam is received bythe sensor element through the light window. The light window may be amere slit but not be limited thereto. It may be formed of anylight-permeable material unless it disturbs the detection of Ramandisperse rays.

[0050] Alternatively, the conveyor means may be an endless conveyor andthe sensor element may be disposed at a predetermined position on a sideof the conveying path constituted by the endless conveyor, and thedistance determination mechanism comprises a stopper member having alight window and disposed in front of the sensor element in the vicinitythereof and a guide for guiding the polymer product carried on theendless conveyor so that the polymer product is pushed against the lightwindow of the stopper member to be able to pass by a front of the sensorelement.

[0051] The stopper member has a function for limiting the displacement(deviating from the conveying direction) of the polymer pushed towardthe stopper member by the guide while being conveyed on the endlessconveyor at the position of the stopper member. The stopper member isprovided with the light window, behind which is located the sensorelement.

[0052] According to this arrangement, the polymer conveyed on theendless conveyor is guided by the guide to be brought into contact withthe light window of the stopper member and irradiated with a light beamthrough the light window. The reflected or dispersed beam thereof isreceived by the sensor element through the light window. The lightwindow may be a mere slit or be formed of any light-permeable materialsuch as transparent glass plate not disturbing the detection of Ramandisperse rays.

[0053] To achieve the above objects, one aspect of a method for cleaningthermoplastic resinous products comprises the steps of crushing thecollected thermoplastic resinous products into crushed pieces, supplyingthe crushed pieces together with water into a cleaning device having avessel and a rotary body disposed in a rotatable manner within thevessel, wherein at least part of the inner surface of the vessel and/ora surface of the rotary body to be in contact with the crushed resinouspieces is roughened, and rotating the rotary body to clean the crushedpieces.

[0054] According to this cleaning method, at least part of the innersurface of the vessel and/or a surface of the rotary body is roughened.The roughening may be carried out in any manners, provided the resinproduct could be sufficiently cleaned. Preferably, the surfaceirregularity has a depth in a range from 40 to 2000 μm. When theroughened surface is brought into contact with the crushed resinouspieces, foreign matters such as coated film or label adhered on thesurface of the crushed resinous piece are sufficiently scrubbed orscraped off and removed. If the depth of the irregularity is less than40 μm, the foreign matters are not sufficiently removable, while ifexceeding 2000 μm, the surface of the crushed resinous piece isexcessively scraped off together with resin to lower the recoverypercentage of resin. The depth of the irregularity is preferably in arange from 50 to 1000 μm, more preferably from 60 to 500 μm. If thedepth is within this range, the foreign matters are sufficiently removedwithout excessively scraping resin off from the crushed piece.

[0055] The roughened surface in the interior of the vessel is preferably1% or more, preferably 5% or more, more preferably 10% or more of atotal area of the inner surface of the vessel and the surface of therotary body to be in contact with the crushed resinous pieces. Degreesof the surface-roughening by the irregularity may be approximately equalor unequal both in the inner surface of the vessel and in the surface ofthe rotary body. The degree of the irregularity may be equal or unequalthroughout the roughened inner surface of the vessel and/or theroughened surface of the rotary body.

[0056] According to this cleaning method, water is continuously suppliedduring the cleaning operation and acts as a lubricant between thesurface of the crushed resinous piece and the roughened surface havingthe irregularity to prevent the surface of the crushed resinous piecefrom excessively being scraped off. Also, by the cooling action ofwater, the temperature rise in the crushed resinous piece can beprevented. Foreign matters such as coated film or label which have beenonce removed are quickly discharged out of the cleaning device not toadhere again to the crushed resinous pieces. Further, water ispreferably continuously supplied and drained so that a water level inthe cleaning device is maintained constant, while taking care tomaintain a ratio in weight of the crushed pieces to the water constant,because the respective crushed resinous pieces continuously supplied canbe evenly cleaned.

[0057] The cleaning is preferably carried out so that the ratio inweight of the crushed pieces to the water in the cleaning device iscontrolled to be 1:0.3 to 2 and water is continuously supplied anddrained to maintain the interior temperature of the cleaning device at70° C. or lower. If the ratio of water is less than 0.3, the interior ofthe cleaning device is not sufficiently cooled, whereby the temperaturerises above 70° C. to soften and melt the crushed resinous pieces, whichmay disturb the cleaning operation. On the other hand, if the ratio ofwater exceeds 2, chances of contact of the crushed resinous pieces withthe inner surface of the vessel and the surface of the rotary body,particularly those roughened to have the irregularity, becomes fewer.Even if the contact occurs, the crushed resinous piece does not besufficiently pressed onto the surface, whereby the foreign matters suchas coated film or label may not be completely and effectively removed.

[0058] Further, the rotary body has a screw blade for conveying thecrushed resinous pieces and cleaning plates or pins for cleaning thecrushed resinous pieces around a rotary shaft, and preferably rotates sothat a linear speed of a tip end of the cleaning plate or pin is in arange from 0.5 to 20 m/sec. If the linear speed is 0.5 m/sec or less,the cleaning becomes insufficient, while if exceeding 20 m/sec, theinterior temperature of the device rises, whereby it is difficult tomaintain the temperature at 70° C. or lower.

[0059] According to the above-mentioned method, it is possible to cleanthe crushed pieces of all thermoplastic resin products molded to havepredetermined shapes by various molding methods such as compressionmolding, ejection molding or blow molding. These resin mold products maybe molded either using a mold or using no mold but a mold die or others.Examples of the resin mold product include not only housings of homeelectric appliances such as TV sets or electric refrigerators orhousings of OA equipment such as personal computers or printers but alsoparts of these apparatuses and/or broken ones thereof.

[0060] Although there is no limitation in kinds and shapes of the resinproducts, preferably, products of different kinds of resins are notmixed together. This is because, if different kinds of resins are mixedtogether, in general, characteristics inherent to the respective resinare largely deteriorated. Therefore, the resin products are preferablyclassified to the respective kinds and separately cleaned in advance.Also, the resin products may preferably be classified to have the sameor similar color tones, such that products which color tones are largelydifferent, for example, one being pale and light gray and the otherbeing deep and dark gray, are not mixed together. If the products havinglargely different color tones are not mixed together, color tone ofresin to be reused is easily adjustable.

[0061] Also, there is no limitation in size of the resin products,provided they can be crushed to pieces of a suitable size.

[0062] The resin products may be coated or plated. The coated film maybe of any material usually used for coating resin. The plated layer maybe of any metal usually used for plating resin.

[0063] The resin product is cleaned after being crushed into resinouspieces through a crushing operation in advance. The crushing operationmay be carried out by a crusher usually used for crushing resin andcapable of crushing the resin product into pieces of a size suitable forthe cleaning, such as a hammer mill or a cutter mill. The crushingoperation is preferably carried out under the forced cooling such as aircooling so that the resin product does not melt due to the heatgeneration.

[0064] The maximum length of the crushed resinous piece is preferably ina range from 1 to 30 mm, more preferably from 2 to 20 mm, mostpreferably from 3 to 10 mm. If the maximum length is less than 1 mm,micro-particles increases to dissipate the crushed resinous pieces in apre-treatment process. On the other hand, if exceeding 30 mm, thecleaning becomes insufficient all over the surface of the crushed piece.There is no limitation in shape of the crushed resinous piece providedno problem occurs in the handling thereof. However, an excessivelyelongated one is unfavorable, and one having generally equal dimensionsin all directions in a plan view is preferable, such as circular orsquare. Crushed resinous pieces of such a shape can be effectivelycleaned even if an amount thereof is large. In this regard, ifnecessary, small crushed resinous pieces having the maximum length ofapproximately 1 mm or less, metallic powder or dust may be removed aftercrushing by a vibratory screen or others.

[0065] To achieve the above objects, in the cleaning system according tothe present invention, a device is provided for cleaning thermoplasticresinous products comprising a vessel and a rotary body built-in in thevessel, wherein the vessel has an entrance port for the thermoplasticresinous products provided in an upper area of one end thereof, an exitport for the thermoplastic resinous products provided in a lower area ofthe other end thereof, a water supply port and a drainage port; thedrainage port being connected to a drainage line for adjusting a waterlevel; the rotary body having a rotary shaft, a screw blade provided onthe circumference of the rotary shaft and at least one of a plurality ofcleaning plates and cleaning pins; and at least part of the innersurface of the vessel and/or surfaces of at least one of the cleaningplates and the cleaning pins being roughened.

[0066] Also, to achieve the above objects, in the cleaning systemaccording to the present invention, a device is provided as anotheraspect for cleaning thermoplastic resinous products comprising a vesseland agitating blades, wherein the vessel has an entrance port forcrushed resinous pieces and a water supply port, both provided in anupper portion thereof, and an exit port for the crushed resinous piecesand a drainage port, both provided in a lower portion provided thereof;a drainage line for adjusting a water level being connected to thedrainage port, and at least part of the inner surface of the vesseland/or surfaces of the agitating blades being roughened.

[0067] According to the above-mentioned cleaning device, at least partof surfaces to be in contact with the crushed resinous pieces isroughened to effectively scrub or scrape off a surface portion of thecrushed resinous piece and sufficiently remove foreign matters such ascoated film, plated layer applied to the surface, label or seal adheredto the surface or contaminants. At least part of the inner surface ofthe vessel and/or a surface of at least one of the screw blade, thecleaning plate and the cleaning pin may be roughened. Preferably, theinner surface of the vessel and a surface of at least one of the screwblade, the cleaning plate and the cleaning pin are roughened. Regardingthe screw blade, the cleaning plate and the cleaning pin, a surface ofat least one of the screw blade and/or the cleaning plate is morepreferably roughened. Also, the inner surface of the vessel and at leastpart of a surface of the agitator blade is preferably roughened.

[0068] If necessary, the cleaning device may be combined with a waterrinsing device, a dehydrator, a dryer, a vibratory screen, a wind typeclassifier and/or a metal sensor to assuredly remove foreign matterssuch as coated film, label or contaminants and obtain pure crushedresinous pieces. Such crushed resinous pieces may be used in any fieldrequiring the same with no problems.

[0069] The above and other objects, effects, features and advantages ofthe present invention will become more apparent from the followingdescription of embodiments thereof taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0070]FIG. 1 is a block diagram for schematically illustrating a resinrecycling system according to the present invention;

[0071]FIG. 2 is a schematic view of one embodiment of crushing means andclassifying means used in the present invention;

[0072]FIG. 3 is a schematic side view of one example of a crusher usedin the present invention;

[0073]FIG. 4 is an enlarged view of part of FIG. 3;

[0074]FIG. 5A is a front view of an opposite wall; FIG. 5B is asectional view taken along a line 5B-5B in FIG. 5A; FIG. 5C is a planview of a connecting plate of a chain conveyor; and 5D is a sectionalview taken along a line 5D-5D in FIG. 5C;

[0075]FIG. 6A is a schematic side view of another example of a crusher;and FIG. 6B is a schematic side view of a still further example thereof.

[0076]FIG. 7 is a block diagram illustrating the relationship betweeninputs and outputs of a controller for the system shown in FIG. 2;

[0077]FIG. 8 is a flow chart illustrating one example of a procedure forcontrolling the identification and classification/recovery of resins;

[0078]FIGS. 9A and 9B are a side view and a top view, respectively, ofone example of a polymer conveying mechanism provided with anidentification device;

[0079]FIG. 10 is a sectional view taken along a line 10-10 in FIG. 9A;

[0080]FIGS. 11A and 11B are a side view and a top view of anotherexample of a polymer conveying mechanism provided with an identificationdevice;

[0081]FIG. 12 is a cross-sectional view of one example of a horizontaltype continuous cleaning apparatus according to the present invention;

[0082]FIG. 13 is an elevational sectional view of one example of ahorizontal type continuous cleaning apparatus according to the presentinvention;

[0083]FIG. 14 is a sectional view illustrating a drainage line foradjusting a water level of a cleaning apparatus;

[0084]FIG. 15 is a cross-sectional view illustrating one example of avertical and batch type cleaning apparatus according to the presentinvention;

[0085]FIG. 16 is a block diagram illustrating one embodiment of recoverymeans according to the present invention;

[0086]FIG. 17 is a table showing results obtained by the operation of acrusher;

[0087]FIG. 18 is a table showing results obtained by the operation of aidentification device; and

[0088]FIG. 19 is a table showing results obtained by the operation ofvarious cleaning apparatuses.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0089]FIG. 1 illustrates one embodiment of a resin recycling systemaccording to the present invention.

[0090] The illustrated system includes a crushing system 200, aclassification system 400, a cleaning system 600 and a recovery system800. The crushing system 200 operates to crush resinous mold productsone by one into pieces so that 70% or more of the pieces have anequivalent diameter in a range from 1 to 50 mm, and to pack the piecesof every one mold product to one transparent bag. The classificationsystem 400 operates to irradiate light beams to the crushed resinouspieces in the bag, determine a kind of the crushed resin in accordancewith the reflected beams therefrom and classify the respective bags intothe kinds of resins. The cleaning system 600 operates to clean thecrushed resinous pieces taken out from the respective bags classified bythe classification system 400 to remove foreign matters on the surfaceof the crushed resinous pieces. A mechanism for taking out the crushedresinous pieces from the bag and sending the same to a rinsing mechanismmay be provided. The recovery system 800 operates to separate theforeign matters from a mixture thereof with the cleaned resinous piecesto recover the crushed resinous pieces.

[0091] [1] Crushing system 200 and classification system 400

[0092] Initially, the crushing system 200 and the classification system400 will be described with reference to FIG. 2.

[0093] The crushing system 200 has a resin crusher 21. The resinouspieces crushed by the resin crusher 21 are packed in a transparent bag25 attached at a lower position of the crusher.

[0094] As described later, the classification system 400 has a conveyordevice 49 for the bags 25, a resin identification device (resindetermination device) 41 and classified recovery devices 47 a to 47 c.

[0095] The resin crusher 21 is a device for crushing the resin moldproduct into pieces so that 70% or more of the pieces have an equivalentdiameter in a range from 1 to 50 mm. The resin mold products are crushedinto pieces one by one and packed in the bag 25 attached to a lowerposition of the resin crusher 21. While the resin crusher 21 illustratedin the drawing is of a type carrying out the crushing operation in onestep, the operation may be carried out in two steps if the moldedproduct is too large to be introduced into the ordinary size crusher.For example, a crusher for carrying out the coarse crushing and one forcrushing the coarsely crushed pieces into smaller pieces having anequivalent diameter in a range from 1 to 50 mm may be provided.

[0096] The bag 25 is made of transparent polyethylene and has a size of23 cm long, 17 cm wide and 40 μm thick. The bag 25 may be opaque andmade of other material than polyethylene unless the identification ofthe crushed resin is disturbed thereby in a resin identification device41 described later. Also, the bag may be a non-film type.

[0097] Here, the preferred embodiment of the crusher will be described.FIG. 3 is a schematic side view of one example of a crusher used in thepresent invention; FIG. 4 is an enlarged view of part of FIG. 3; FIG. 5Ais a front view of an opposite wall; FIG. 5B is a sectional view takenalong a line 5B-5B in FIG. 5A; FIG. 5C is a plan view of a connectingplate of a chain conveyor; and FIG. 5D is a sectional view taken along aline 5D-5D in FIG. 5C. FIG. 6A is a schematic side view of anotherexample of a crusher; and FIG. 6B is a schematic side view of a stillfurther example thereof.

[0098] The crusher illustrated has a chain conveyor (endless conveyor)220 and an opposite wall (opposite member) 250. The chain conveyor 220transports articles carried on connecting plates 221 attached to a chain225 driven by sprockets 227, 227, by displacing the connecting plates221. This chain conveyor 220 is disposed to have a downward inclinationtoward the conveying direction indicated by arrow in the drawing totransport the polymer mold products introduced into the crusher from amaterial introduction port 232 provided at an upper position of thecrusher, while carrying the mold products on the connecting plates 221.As shown in FIG. 5C, a plurality of crushing edges 222 (in the drawing,two rows of eighteen edges) are provided on the respective connectingplate 221 of the chain conveyor 220 with sharp ends thereof projectingout of the conveyor. In this regard, instead of the crushing edges 222,crushing pins may be provided.

[0099] The opposite wall 250 extends in the vertical direction and hasan opposite surface 255 opposed to an end portion of the chain conveyor220 as seen in the conveying direction (a left end portion in FIG. 3).In the vicinity of a point at which this opposite surface 255 is closestto the chain conveyor 220 (in the vicinity of the lower end in thedrawing), a plurality of crushing edges 252 are provided while directingtoward the chain conveyor 220. In this regard, instead of the crushingedges 252, crushing pins may be provided. As shown in FIG. 5, thecrushing edges 252 on the opposite wall 250 and the crushing edges 222on the chain conveyor 220 are provided to have different phases fromeach other not to collide with each other even though both the crushingedges most closely approach. In the opposite wall 250, slits 256 areprovided so that tip ends of the crushing edges 222 on the chainconveyor 220 can enter the same not to collide with the opposite wall250 when the crushing edges 222 most closely approach the opposite wall250. FIG. 4 illustrates a manner in which the crushing edges 222 of thechain conveyor 220 most closely approach the opposite wall 250 and thetip ends of crushing edges 222 enter the slits 256.

[0100] In the crusher thus structured, the polymer mold productsintroduced from the material introduction port 232 into the crusher andconveyed by the chain conveyor 220 are sheared by the crushing edges 222and 252 and roughly crushed while being compressed into a zone in whichthe chain conveyor 220 and the opposite wall 250 are close to eachother.

[0101]FIG. 6A illustrates a variation of FIG. 3. The crusher shown inFIG. 6A is provided with a guide 259 at a lower end of the opposite wall250. This guide 259 operates, when the mold product conveyed by thechain conveyor 220 is of a flat-shape and oriented in the verticaldirection, to prevent the mold product from escaping from thecompression caused by the chain conveyor 220 and the opposite wall 250and the shearing action of the crushing edges 222, 252 and falling downwhile not being crushed.

[0102] In this regard, while the crushing edges are provided both in thechain conveyor 220 and the opposite wall 250 in the embodiments shown inFIGS. 3 and 6A, they may be provided in at least one of the both.However, if they are provided in both of them, the shearing action ofthe crushing edges is more enhanced.

[0103] In a crusher shown in FIG. 6B, two chain conveyors 220 and 250 aare provided so that a distance between the both becomes graduallysmaller in the conveying direction. According to this crusher, the upperinclined chain conveyor 250 a has a function as the opposite member. Thecrushing edges 222 and 252 a of the respective conveyors 220 and 250 areprovided to have different phases from each other not to collide witheach other even though both the crushing edges most closely approach

[0104] While two chain conveyors 220, 250 a have crushing edges 222, 252a, respectively, in the embodiment shown in FIG. 6B, these may beprovided on at least one of the conveyors. If the crushing edges areprovided on both the conveyors, the shearing operation of the crushingedges can be more assuredly carried out. In the arrangement shown inFIG. 6B, the upper chain conveyor 250 a may be replaced with a slantedopposite wall having the same inclination as the conveyor 250 a.Alternatively, rollers may be provided. That is, it is sufficient thatthere is an arrangement for transporting the polymer mold products bythe conveyor means and pushing the same into a gap between the conveyormeans and the opposite member so that the mold products are roughlycrushed while being compressed by the crushing edges or pins.

[0105] In this regard, a continuous system may be arranged from thearrangement shown in FIG. 3 or 6 by providing a fine crusher (for morefinely crushing the coarsely crushed pieces) subsequent thereto.

[0106] Now return to FIG. 2 wherein the conveyor device 49 transportsthe bags in which the crushed resinous pieces are packed at apredetermined speed V and stops the same if necessary. If it is expectedthat a more time is required for the identification of resin, forexample, because of a slow calculating speed of the resin identificationdevice 41 (described later), the stop of the conveyor device will benecessary. The conveyor device 49 may include a conveyor with trays andif an expected arrival time has been reached, the corresponding tray isinclined to throw down the bag carried thereon into a recovery boxbeneath the same. The expected arrival time is a time instant obtainedby adding a time period necessary for a certain bag in which a resin ofkind A are packed to be conveyed to a recovery box for the resin A to atime instant at which the resin in the bag has been identified as A. Thecorresponding tray is a tray on which the certain bag is placed. In thisregard, while the crusher 21 and the conveyor device 49 (and the resinidentification device 41 or others) are provided in the same factory inFIG. 2, the both may be provided in different factories, respectively,such that the resinous pieces crushed by the crusher 21 and stuffed inthe bag 25 are transported to the factory in which the conveyor device49 or others is provided. In other words, even in such an arrangement,it is possible to suppress the transportation cost to a lower levelbecause the resin is reduced in volume.

[0107] The resin identification device 41 is a device for identifying akind of the crushed resinous pieces in the bag 25 based on a Ramanspectrum analysis. That is, a laser beam is irradiated to the crushedresinous pieces in the bag 25 which passes a detection position(identification position) (or is made to stop for a while if a timeperiod is required for the identification), and reflected therefrom. ARaman spectrum is obtained from the reflected beam and sequentiallycompared with Raman spectra of known resins to find the coincidence ofRaman spectra of both the resins to decide a kind of resin in the bag.For this purpose, the resin identification device 41 stores Ramanspectra of various resins obtained in advance.

[0108] The classified recovery device 47 a is for a resin A. Similarly,the classified recovery device 47 b is for a resin B, and the classifiedrecovery device 47 c is for a resin C. If there are four kinds of resinsor more, the number of classified recovery devices may becorrespondingly increased. A distance between theclassification/recovery position of the classified recovery device 47 aand the detection position of the resin identification device 41 is a; adistance between the classification/recovery position of the classifiedrecovery device 47 b and the detection position of the resinidentification device 41 is b; and a distance between theclassification/recovery position of the classified recovery device 47 cand the detection position of the resin identification device 41 is c.When a current time reaches the expected arrival time, the classifiedrecovery device corresponding to the kind of resin in correspondence tothat expected arrival time is operated to recover the bag located at theclassification/recovery position of that classified recovery device intothe recovery box.

[0109] The classified recovery device is not limited to the illustratedone in which a tiltable tray of the conveyor is inclined to throw downthe bag into the recovery box disposed beneath the conveyor. Forexample, a manipulator may be provided above the conveyor and lift thebag on the conveyor to recover the same. Alternatively, a pusher may beprovided for pushing the bag on the conveyor aside by a rod or the like.Or, the classified recovery devices may not be individually provided incorrespondence to kinds of resins, but all the bags may be recovered bya single recovery device, from which the bags are distributed into therespective recovery boxes in correspondence to the kinds of resins.

[0110]FIG. 7 is a block diagram illustrating the relationship betweeninputs and outputs of a controller for the system, and FIG. 8 is a flowchart illustrating a procedure for controlling the identification andclassification/recovery of resins. The description will be made belowwith reference to FIGS. 7 and 8.

[0111] First, the conveyor device 49 starts (S01).

[0112] When the identification result (a kind of resin in the bag 25passing through the identification position or stopping in a periodnecessary for the identification at the identification position) isinput from the resin identification device 41 (i.e., the answer is YESat S11), the expected arrival time at which the bag (packing theidentified resin) reaches the classified recovery device (for example,the device 47 a) is calculated based on a current time obtained from aclock IC 43, a distance to the classified recovery device determined inaccordance with a kind of the identified resin (if the identified resinis a kind A, this distance is a to the classified recovery device 47 a)and a conveying speed V of the conveyor device 49, and stored in amemory (not shown) within a controller 45 in correspondence to the resinkind A (i.e., to the classified recovery device 47 s) (S13). In thisregard, since the conveying speed V and the distance (a/b/c) are known,a time period necessary for the transportation determined in accordancewith kinds of resins may be added to the current time, instead ofcarrying out the above calculation.

[0113] If the current time reaches either one of the expected arrivaltimes stored in the memory (not shown) of the controller 45 (i.e., ifthe answer is YES at S21), an operation command is issued from thecontroller 45 to the classified recovery device stored in correspondenceto this expected arrival time. Thereby, the above-mentioned classifiedrecovery device is operated to recover the bag located at theclassification/recovery position of the classified recovery device(S23). Thereafter, the expected arrival time and data of the classifiedrecovery device stored in correspondence thereto are deleted from thememory (S25).

[0114] Other preferred embodiments of the resin identification devicewill be described in more detail below with reference to FIGS. 9 to 11.

[0115] (1) First Embodiment

[0116]FIGS. 9A, 9B and 10 schematically illustrate a first embodiment ofa polymer conveying mechanism provided with an identification device,wherein FIG. 9A is a side view, FIG. 9B is a top view and FIG. 10 is asectional view taken along a line 10-10 in FIG. 9A. In the drawings,reference numeral 410 denotes a polyethylene bag (having a size of 23 cmlong, 17 cm wide and 40 μm thick) in which resin pieces crushed to havea suitable size (for example, so that 70% or more of the pieces have anequivalent diameter in a range from 1 to 50 mm) are packed, wherein theequivalent diameter is a diameter of a circle having the same area as aprojected area of an object.

[0117] The bag 410 is conveyed on a conveyor belt 440 driven by driverollers 441, 441 in the arrowed direction, and irradiated with a laserbeam from a sensor element 421 in the midway of its travel, whereby aRaman scattering can be detected. The detected signal is fed to anidentification and calculation device 420 in which a kind of resin isidentified. That is, the detected Raman spectrum is sequentiallycompared with those of various known resins stored in advance until theknown resin coinciding with the resin to be identified is found. Basedon the identification result, a timing for a dispensing operation iscalculated and a dispensing device 430 is operated at the calculatedtiming. Thereby, the bag 410 is removed from the conveyor belt 440 andput into a vessel in correspondence to a kind of the identified resin(either one of vessels 435 a, 435 b and 435 c). The dispensing timing isa timing at which the bag 410 of which the Raman scattering has beendetected at a position of the sensor element 421 to identify the kind ofresin reaches the vessel (either one of vessels 435 a, 435 b and 435 c)corresponding to the kind of resin packed in the bag.

[0118] According to the first embodiment, as illustrated, a plurality ofslits 400S of a predetermined length used as a light window for allowinga light beam to pass through the same (having a size of 10 mm wide and20 cm long) are arranged along a center portion of the width of theconveyor belt 440 at a predetermined pitch in the belt-runningdirection. The above-mentioned sensor element 421 is disposed at aposition in correspondence to the slit position beneath the conveyorbelt 440 in the vicinity of the inner surface of the conveyor belt 440.Thus, it is possible to maintain a distance between the light-receivingpart of the sensor element 421 and the bottom surface of the bag 410always at a predetermined short distance (for example, approximately 10mm) capable of detecting the Raman scattering, irrespective of shapes ofthe bags 410. Thereby, the high-precision resin identification can becarried out.

[0119] In this regard, a member for pressing the bag 410 onto the uppersurface of the conveyor belt 440 may be provided at a position above thesensor element 421 to prevent the bottom surface of the bag 410 fromfloating upward from the upper surface of the conveyor belt 440, so thatthe above-mentioned distance between the light-receiving part of thesensor element 421 and the bottom surface of the bag 410 is maintainedconstant.

[0120] (2) Second Embodiment

[0121]FIG. 11 schematically illustrates a second embodiment of a polymerconveying mechanism wherein FIG. 11A is a side view and FIG. 11B is atop view. In the drawings, the same reference numerals are used fordenoting the same or similar parts as those in FIG. 9, and theexplanation thereof will be eliminated.

[0122] According to the second embodiment, as illustrated, a windowplate 422 having a light window for allowing a light beam to passthrough the same is disposed at a position on the lateral side of aconveyor belt 440 a, and is also used as a stopper member. A sensorelement 421 is provided at a position on a side of the window plate 422opposite to the conveyor belt 440 a so that the light receiving part ofthe sensor element 421 confronts the window plate 422. At a positionopposite to the window plate 422, a plate-like curved guide 423 isprovided directly above the conveyor belt 440 a, while interposing theconveyor belt between the window plate and the curved guide. This guide423 operates to push the bag 410 transported on the conveyor belt 440 atoward the window plate 422 and cause the bag 410 to be in contact withthe window plate 422. According to this structure, it is possible tomaintain a distance between the light-receiving part of the sensorelement 421 and the lateral surface of the bag 410 at a thickness of thewindow plate 422 (for example, approximately 10 mm), irrespective ofshapes of the bags 410. In other words, it is possible to maintain thedistance at a value as small as capable of detecting the Ramanscattering. Thereby, the high-precision resin identification can becarried out.

[0123] Instead of the guide 423 formed of a curved plate as in theillustrated embodiment, one or two rollers or more may be used for thesame purpose. In such a case, the roller may be either a freelyrotatable type or one driven to rotate in synchronism with the conveyorbelt 440 a.

[0124] While an endless belt is used as a conveyor means in theabove-mentioned embodiment, the conveyor means according to the presentinvention should not be limited to the endless belt, provided it iscapable of transporting the polymer to be detected while maintaining apredetermined short distance between the light-receiving part of thesensor element 421 and the polymer. For example, the conveyor means maybe of a type for transporting the bag 410 carried on a tray.

[0125] [2] Rinsing system 600

[0126] Next, the cleaning system 600 will be described.

[0127] FIGS. 12 to 14 illustrate a structure of the continuous cleaningdevice 600, wherein FIG. 12 is a schematic cross-sectional view, FIG. 13is a schematic side sectional view and FIG. 14 is a detailedillustration of a drainage line 669 for adjusting a water level.

[0128] The continuous cleaning device 600 has a vessel 660 and rotarybodies 662. In FIGS. 12 and 13, the vessel 660 may be formed of a metalsuch as stainless steel. An entrance port 663 for crushed resinouspieces is provided at one end of an upper wall of the vessel 660, and anexit port 668 for the crushed resinous pieces is provided in a lateralwall on the opposite end side. A water feeding port 664 is provided atat least one position of the upper wall of the vessel 660, and adrainage port 666 is provided at at least one position of the lower wallof the vessel 660. A drainage line 669 for adjusting a water level isconnected to the drainage port 666.

[0129] A predetermined amount of crushed resinous pieces is continuouslyintroduced into the vessel 660 through the entrance port 663, conveyedalong the same and discharged from the exit port 668. In this process,preferably, the introduction speed and the discharge speed of thecrushed resinous pieces are approximately equal to each other andmaintained roughly constant. A feeding speed of water to be suppliedfrom the water feeding port 664 is preferably controlled so that a waterlevel determined by the water level adjusting pipe 669 b is maintained,while taking a draining speed of water from an open end of the waterlevel adjustment drainage line 669 into account. By adjusting theintroduction and discharge speeds of the crushed resinous pieces andthose of water, constant amounts of crushed resinous pieces and waterare always conveyed through the vessel 660. Accordingly, the crushedresinous pieces are evenly cleaned and, as a result, the surfaces of thecrushed resinous pieces are free from the foreign matters left thereon,and prevented from being excessively scraped off.

[0130] In the drainage port 666 provided in the bottom wall or others ofthe vessel 660, slits or punched plate are disposed. Also, in thedrainage port 666, the water level adjustment drainage line 669 isconnected. The water level adjustment drainage line 669 has a drainagepipe 669 a connected to the drainage port 666 and standing upward on thelateral side of the vessel 660 and a water level adjustment pipe 669 bfitted to the interior of the drainage pipe 669 a in a slidable manner.Between the inner surface of the drainage pipe 669 a and the outersurface of the water level adjustment pipe 669 b, an O-ring 669 c isinterposed to keep the water-tight sealing. By moving the water leveladjustment pipe 669 b upward and downward, it is possible to adjust thewater level in the cleaning device 600 and maintain a predeterminedwater level.

[0131] While the water feeding port 664 and the drainage port 666 areprovided at one position, respectively, in the illustrated embodiment,they may be provided at a plurality of positions, respectively. When thewater feeding ports 664 are provided at a plurality of positions fromone end to the other end of the vessel 660, it is possible to quicklyguide dust or others generated by the cleaning operation to the drainageports 666 and drain the same outside through the water level adjustmentline 669. Further, it is also possible to prevent the dust or othersfrom sticking again to the crushed resinous pieces.

[0132] Openings provided in the drainage port 666 such as slits or holesof a punched plate have a size to allow water or dust to pass throughthe same but prevent the crushed resinous pieces from passing. The slitis preferably of a size in a range from approximately 0.3 to 2 mm inview of the mechanical strength. While the drainage port 666 may beprovided in either of the bottom wall or the lateral wall, the bottomwall is preferable in view of the adjustment of the water level. In thisregard, if the drainage port is provided in the lateral wall, theposition thereof is preferably as low as possible, of course.

[0133] An open end of the water level adjustment pipe 669 b opens to theatmosphere so that the water level in the vessel 660 is generally equalto a height of the open end of the water level adjustment pipe 669 b.Thereby, even if the feed rate of water varies, the water level ismaintained constant and excessive water is drained from the open end ofthe water level adjustment pipe 669 b. The drained water may beaccumulated in a tank and reused after being pumped up and filtratedthrough a filter to remove dust or others therefrom.

[0134] The rotary shaft 662 is provided with screw blades 662 c forcleaning the crushed resinous pieces while conveying the same from theentrance port 663 to the exit port 668, and cleaning plates 662 a andcleaning pins 662 b for scrubbing or scraping off foreign matters fromthe surface of the crushed resinous pieces while imparting shockthereto, all of which are alternately arranged. Either one of thecleaning plate 662 a or the cleaning pin 662 b may be eliminated,although the combined use thereof is preferable.

[0135] A diameter of the screw blade 662 c, a thickness of the cleaningplate 662 a and a length of the cleaning pin 662 b are not limited,provided the efficient cleaning is achievable. The screw blades 662 cmay have a generally equal diameter; the cleaning plates 662 a may havegenerally equal diameter and thickness; and the cleaning pins 662 b mayhave a generally equal length. Also, the number of screw blades 662 cfor cleaning the crushed resinous pieces while conveying the same ispreferably two or three per one zone. An axial length of the screw blade662 c per one zone is preferably 0.5 to 3 relative to a diameter. Whilethese screw blades 662 c, the cleaning plates 662 a and the cleaningpins 662 b are alternately arranged, the number thereof disposed in onezone may be equal in all zones or different from those of other zones.

[0136] A pitch of the screw blades 662 c must be determined by taking arotational speed of the rotary shaft into account. Since the rotaryshaft is necessarily made to rotate at a relatively high speed foreffectively abrading and cleaning the crushed resinous pieces, the pitchis preferably in a range from 0.3 D to 1.5 D wherein D represents adiameter of the screw blade 662 c. If the pitch is less than 0.3 D, agap between adjacent two screw blades is so small that the crushedresinous pieces may be caught in the gap and rotate together with thescrew blades to disturb the transportation or the cleaning. Also, thecrushed resinous pieces caught in the gap may melt to disable thecontinuation of cleaning operation. On the other hand, if the pitchexceeds 1.5 D, the conveying efficiency is lowered. In this regard, whenthe conveying efficiency of the screw blade 662 c is excessively largeand thus a dwell time of the crushed resinous pieces becomesinsufficient in the area wherein the cleaning plates 662 a or thecleaning pins 662 b are provided, part of the screw blade may be cut offso that a balance is adjustable between the conveying capacity and thecleaning operation.

[0137] Shapes of the cleaning plate 662 a are not limited. For example,the cleaning plate may be circular or polygonal, such as triangular orquadrangular, as seen in the axial direction of the rotary shaft 662.The cleaning plate 662 a is not necessarily symmetric in shape withrespect to the rotary shaft 662. Also, it may be slanted to the rotaryshaft 662 to have a conveying function. The cleaning plates inclined inthe conveying direction and in the opposite direction thereto may becombined with each other to enhance the cleaning efficiency. The same istrue to the cross-sectional shape of the cleaning pin 662 b, which maybe circular or polygonal such as triangular or quadrangular. Thepolygonal cross-section is favorable because the cleaning efficiencybecomes higher. The cleaning pin 662 b is not necessarily projectedvertical to the circumference of the rotary shaft 662 but may beinclined at a proper angle.

[0138] The rotational speed of the rotary shaft 662 has a proper rangevariable in accordance with sizes of devices, kinds of crushed resinouspieces or degrees of cleaning demanded. Generally, a linear speed of atip end of the cleaning plate 662 a or the cleaning pin 662 b ispreferably in a range from 0.5 to 20 m/sec, more preferably from 1 to 10m/sec. In the rotational speed under which the linear speed is less than0.5 m/sec, it is impossible to sufficiently clean the surface of thecrushed resinous piece even if the treatment time is prolonged.Contrarily, if the linear speed exceeds 20 m/sec, the interiortemperature of the cleaning device rises to soften and be liable to meltthe crushed resinous pieces, which is unfavorable because a largedriving power is necessary.

[0139] At least part of surfaces to be in contact with the crushedresinous pieces; that is, the inner surface of the vessel 660 andsurfaces of the screw blade 662 c, the cleaning plate 662 a and thecleaning pin 662 b; is roughened to constitute an abrasive surface.Accordingly, the foreign matters on the surface of the crushed resinouspiece can be efficiently scrubbed or scraped off. A depth of theirregularity on the roughened surface is preferably in a range from 40to 2000 μm, more preferably from 50 to 1000 μm, most preferably from 60to 500 μm. If the depth is less than 40 μm, the foreign matters couldnot be sufficiently removed. On the other hand, if exceeding 2000 μm,the surface of the crushed resinous piece is excessively scraped off tounfavorably lower the recovery percentage of resin. A degree of theabove-mentioned surface-roughening is not necessarily constant from theentrance port 663 to the exit port 668. The cleaning efficiency may beadjustable, for example, by changing the roughening degree to be coarsertoward the entrance port 663 and relatively smoother toward the exitport 668. Also, the cleaning efficiency may be enhanced, for example, bymixing various abradants with water.

[0140] While a two-shaft type cleaning device is illustrated in thedrawing, this is merely one example and a single-shaft type or amulti-shaft type including a three- or more shaft type may be adopted.When the single-shaft type is adopted, however, the movement of thecrushed resinous pieces becomes monotonous in the device to lower thecleaning efficiency. Contrarily, the device having three shafts or moreis complicated in structure and expensive.

[0141] An interior space of the cleaning device may be suitably designedin accordance with throughputs or others thereof. An interior dimensionof the vessel 660 in the direction vertical to the rotary shaft 662 maybe suitably selected in accordance with a diameter of the screw shaft662 c and a necessary gap between the inner surface of the vessel 660and a tip end of the screw blade 662 c. An axial dimension of the rotaryshaft 662 is 5 to 30 times, preferably 10 to 30 times a diameter of thescrew blade 662 c.

[0142] If the axial dimension is less than five times the diameter ofthe screw blade 662 c, the crushed resinous pieces are conveyed to theexit port 668 with part of them being not sufficiently cleaned, whichdegrades the quality of recycled resin material due to the mixture ofthe insufficiently cleaned crushed resinous pieces. If the axialdimension exceeds 30 times the diameter of the screw blade 662 c, themechanical strength of the rotary shaft 662 must be increased or asupport system thereof must be changed, which makes it difficult toprevent the inner surface of the vessel 660 from coming in contact withthe screw blade 662 c or others and increases a cost of the device to agreat extent.

[0143] While the above description has been made on a continuous typecleaning device, a batch type may be adopted. FIG. 15 illustrates abatch type cleaning device of a vertical type as one example thereof.

[0144] A vessel 661 is preferably cylindrical and formed of a metal suchas stainless steel. An entrance port 663 for introducing crushedresinous pieces is provided on the upper surface of the vessel 661, andan exit port 668 for discharging the crushed resinous pieces is providedon the bottom surface thereof. A piston-shaped valve 621 is provided inthe exit port 668, so that the valve is flush with the bottom surface ofthe vessel body when the valve is closed. After the cleaning hascompleted, the piston-shaped valve 621 is opened to take the crushedresinous pieces out of the vessel.

[0145] On the lateral surface of the vessel 661, a water supply port 664is provided at an upper position and a drainage port 666 is provided ata lower position. A water level adjustment drainage line 669 shown inFIG. 14 is connected to the drainage port 666. Alternatively, the watersupply port 664 may be provided on the upper surface of the vessel 661,and the drainage port 666 may be provided on the lower surface of thevessel 661. While the drainage port 666 is formed throughout a lowerarea of the lateral surface of the vessel 661 in FIG. 15, it may beprovided on part of the lower area of the lateral surface. Further,there is no limitation in positional relationship between the entranceport 663 and the exit port 668, but they are preferably provided on adiagonal of the cross-section of the vessel 661. If so, all the crushedresinous pieces are evenly and efficiently cleaned.

[0146] There is no limitation in shape of an agitator blade 603, but apaddle type blade or a lattice type blade having a large surface area ispreferably used. The agitator blades 603 are arranged at a center of thevessel 661, and at least part of the inner surface of the vessel 661 andthe surface of the agitator blade is roughened. A degree of thisroughening, a ratio between the crushed resinous pieces and water and asize of openings such as slits or holes of a punched plate provided inthe drainage port 666 are similar to those in the above-mentionedhorizontal type continuous cleaning device.

[0147] [3] Recovery system 800

[0148] Then, the description will be made on the recovery system 800.

[0149] The recovery system 800 operates to separate foreign matters froma mixture of the foreign matters and crushed resinous pieces cleaned bythe cleaning system 600 and recover the crushed resinous pieces. Therecovery system 800 may include various systems; for example, a systemfor removing metallic material by using magnetic force, a system forremoving foreign matters by rinsing and a system for removing foreignmatters with wind.

[0150] A device illustrated in FIG. 16 separates the crushed resinouspieces from the foreign matters by rinsing the mixture thereof withwater, discharges the foreign matters thus separated together with waterand recovers the remaining crushed resinous pieces.

[0151] On the surface of the crushed resinous piece cleaned by thecleaning system 600 as described above, foreign matters (dust derivedfrom coated film, plated layer or label) scrubbed or scraped off fromthe crushed resinous pieces by the cleaning operation are adhered. Thismixture (of the crushed resinous particles and the foreign matters) isinitially introduced into a continuous type rinsing device 881 andrinsed with water. Most of the foreign matters adhered to the surface ofthe crushed resinous pieces are removed therefrom together with water inthis process. This water may be reused after being filtrated.

[0152] The crushed resinous pieces thus rinsed are transferred via apipe 882 to a centrifugal dryer 883 in which the dehydration is carriedout. The crushed resinous pieces thus dehydrated are conveyed whilevibrating on a vibratory screen 884, whereby the residual foreignmatters are removed. Thereafter, the pieces are collected by apredetermined recovery means. In this regard, subsequent to thevibratory screen 884, means 889 may be provided for further removingmetallic particles by using magnetic force or foreign matters by usingwind.

[0153] Thus, the recycling of resin is carried out.

EXAMPLES

[0154] Results of the crushing operation carried out by using theabove-mentioned embodiment of the crusher described above are shown inTable 1 of FIG. 17. The specifications of this crusher are as follows:

[0155] Size of entrance port: 300 mm×600 mm

[0156] Width of chain conveyor: 340 mm

[0157] Motor: 5.5 kW

[0158] Rotational speed of conveyor: 50 rpm

[0159] Number of crushing blades in connecting plate: 2 rows×18/a plate

[0160] Opposite member: fixing plate with slits

[0161] I-[1] Example A

[0162] Twenty resinous parts were manually extracted from discardedcopying machines. Although having various sizes and shapes, the partswere all mold products having a plate-thickness of approximately 2 to 3mm. The maximum length thereof was 630 mm. These were classified intotwo groups in accordance with the criterion whether or not the producthas a size in which two of a length, a width and a height are 280 mm×170mm or less.

[0163] [1-1] Five parts had a size of 280 mm×170 mm or less, a totalweight of which was 2.3 kg.

[0164] [1-2] Fifteen parts had a size exceeding 280 mm×170 mm, a totalweight of which was 9 kg.

[0165] These mold products were crushed by the crusher shown in FIG. 3(the specifications of which were as described above).

[0166] Results were shown in Table 1 of FIG. 17. In Table 1, anequivalent diameter of a projection circle in Table 1 is defined as adiameter of a circle having the same area as a projected area of aparticle (see KAGAKU KOGAKU BINRAN, 5th edition, p.219). In thisExample, an image of about 100 particles placed on a flat surface whiletaking care not to overlap with each other was shot, from which thenumber and the individual area are measured by an image-processingtechnique. Then a total of the areas was divided by the number ofparticles to obtain an average area, from which a diameter of a circlehaving the same area is calculated.

[0167] I-[2] Comparative example A

[0168] A trial was made to treat the same resin mold products as used inExample A with a small size crusher UG-280 (effective aperture 280mm×170 mm, 5.5 kW) manufactured by K.K. HORAI and added with a screen of15 mm

[0169] However, the resin mold products in the group [1-2] (exceeding280 mm×170 mm) could not be introduced into the small size crusherUG-280 of K.K. HORAI and thus could not be crushed.

[0170] II-[1] Example B (regarding the identification)

[0171] The following three mold products 1. to 3. of different kinds ofresins (a box having a size of 15 cm×10 cm×10 cm and a thickness of 3mm) were individually crushed by the crusher UG-280 manufactured by K.K.HORAI (with a screen of 20 mm mesh). An average size of the crushedresinous piece was approximately 10 mm as represented by an equivalentdiameter, wherein the equivalent diameter is a diameter of a circlehaving the same area as a projected area of the crushed resinous piece.

[0172] The above crushed resinous pieces are respectively packed inseparate bags (made of polyethylene and having a size of 23 cm long, 17cm wide and 40 μm thick). Kinds of the resins were identified by a resinidentification device (RP-1, manufactured by Spectracode; based on theRaman spectrum analysis), upon which a time required for theidentification was measured. Results are shown in Table 2 of FIG. 18. InTable 2, ∘ represents cases wherein all the samples could be identified,and X represents cases wherein there are samples not identified.

[0173] 1. Acrylonitrile-butadiene-styrene

[0174] 2. Polystyrene

[0175] 3. Polycarbonate/acrylonitrile-butadiene-styrene

[0176] II-[2] Comparative example B (regarding the identification)

[0177] Comparative example B was carried out in the same manner as inExample B, except that the above-mentioned three resin mold products 1.to 3. were crushed all together, not separately, in the crusher and thethree kinds of resinous pieces were identified as they are by the resinidentification device, respectively, without being packed in the bag.Results are shown in Table 2 of FIG. 18.

[0178] In Table 2, the number of test samples was assumed by thefollowing equation:

[0179] Number of test samples=weight of resin mold product beforecrushing/standard weight of crushed piece

[0180] The weight of the resin mold product before crushing was 702 gand the standard weight of the crushed piece was 0.259 g, whereby thenumber of the test samples was 2700. This value is about 900 times thatin Example B. In this regard, an average weight of ten disk-like pieceshaving the equivalent diameter of approximately 10 mm was used as thestandard weight of the crushed piece.

[0181] In Table 2, the time required for the identification was assumedby the following equation:

[0182] Time required for identification=all weights of crushedpieces/weight of crushed pieces which could be identified within oneminute

[0183] All the weights of the crushed pieces was 702 g and the weight ofthe crushed pieces which could be identified within one minute was 5.21g, whereby the time required for the identification was 135 minutes.This value is about 900 times that in Example B. In this regard, in thecrushed pieces having the equivalent diameter of 1 mm or less, therewere those difficult to be positioned to the identification device orimpossible to be identified because the intensity of Raman spectrumbecomes weak.

[0184] Next, an example regarding the cleaning system will be described.

[0185] OA apparatuses collected from the market were disassembled toseparate housings made of ABS resin which were then crushed by using amarketed crusher (UG-280; manufactured by K.K. HORAI, with a screen of10 mm mesh) into crushed resinous pieces and subjected to a cleaningtreatment. There were paper seals on part of the housing and manycontaminants on the surface due to a long time use or the collection,disassembly or classification operation. Hereinafter, such crushedresinous pieces are referred to as crushed pieces (A).

[0186] In a similar manner, housings made of ABS resin and having acoating on the surface thereof were crushed into crushed pieces (B)which were then cleaned.

[0187] III-[1] Example C (regarding the cleaning by the horizontal typecontinuous cleaning device shown in FIGS. 12 and 13)

[0188] (1) Cleaning device used

[0189] A diameter of a screw blade provided on a rotary shaft of thecleaning device was 100 mm and a length of the device was 25 times thediameter of the screw blade; i.e., 2.5 m. A drainage port had slits of1.2 mm wide. A water level was maintained somewhat higher than therotary shaft by the water level adjustment pipe, so that a weight ofcrushed pieces (A) and that of rinsing water are generally equal to eachother.

[0190] Further, the screw blades and cleaning plates constituted bysemicircular disks arranged on the rotary shaft at a pitch of 40 mm witha phase thereof being shifted at 90 degrees to each other werealternately disposed on the rotary shaft so that a ratio of an axiallength to the diameter thereof becomes 2 to 4. Part of the screw bladewas cut off to adjust the conveying capacity. The inner surface of thevessel and the surfaces of the screw blades and the cleaning plates wereroughened to have the irregularity of 50 to 100 μm deep.

[0191] (2) Cleaning operation

[0192] Crushed pieces (A) were introduced into the entrance port of thiscleaning device at a rate of 50 kg/hr. On the other hand, water was fedfrom the entrance port at a rate of 30 kg/hr and also from two waterports provided in the lengthwise intermediate portion of the device.These water supply rates were regulated so that a drainage rate from anopen end of the drainage line becomes 100 kg/hr.

[0193] The cleaning operation was carried out at a rotational speed ofthe rotary shaft of 400 rpm (corresponding to a linear speed of 2.1m/sec at a tip end of the cleaning plate) to obtain a slurry in whichdust such as the paper seals blocked to pass by the slits is mixed withthe treated crushed pieces (A) from the exit port. The slurry wasdispersed on the vibratory screen of 2 mm mesh while spraying water fromabove to separate and remove pieces of the paper seals or dusttherefrom. Thereafter, the crushed pieces were dehydrated through acentrifugal dryer and dried. Then, through a wind classifier, foreignmatters having a small specific weight which could not removed by thewater spray were separated and removed to obtain completely cleanedcrushed pieces.

[0194] (3) Inspection of foreign matters

[0195] Crushed pieces of 10 g were compression-mold between a pair ofclean aluminum foils put in a gap between stainless steel plates at atemperature of 220° C. and a pressure of 4 MPa to result in a sheet ofapproximately 200 mm diameter. Thereafter, the aluminum foils werepeeled off from this sheet, and opposite sides of the sheet wereobserved by a magnifying glass to count the number of foreign matters.Results are shown in Table 3 of FIG. 19.

[0196] III-[2] Comparative example C

[0197] A trial was made to clean the crushed pieces (A) in the samemanner as in Example C, except that water is not used. In a short timeafter beginning the introduction of crushed pieces, however, the crushedpieces began to melt, whereby a load became large to disable theoperation.

[0198] III-[3] Comparative example D

[0199] A rotational speed at which the crushed pieces are not melted wasstudied in Comparative example C, and it was found that such a speed is50 rpm (corresponding to a linear speed of 0.26 m/sec at a tip end ofthe cleaning plate). The cleaning operation was carried out at thisrotational speed in the same manner as in Comparative example C in whichwater is not used. After being cleaned, the crushed pieces (A)discharged from the exit port were post-treated in the same manner as inExample C to separate and remove the foreign matters. Foreign mattersleft in the crushed pieces were observed in the same manner as inExample C. Results are shown in Table 3 of FIG. 19.

[0200] III-[4] Example D

[0201] The crushed pieces (B) were cleaned in the same manner as inExample C except that a water supply rate from the intermediate portionincreases so that a drainage rate is regulated to 200 kg/hr at the openend of the drainage line. After being cleaned, the crushed pieces (B)discharged from the exit port were post-treated in the same manner as inExample C to separate and remove foreign matters. Foreign matters leftin the crushed pieces were observed in the same manner as in Example C.Results are shown in Table 3 of FIG. 19.

[0202] III-[5] Comparative example E

[0203] The cleaning was carried out in the same manner as in Example Dexcept that the rotational speed of the rotary shaft decreases to 50rpm. After being cleaned, the crushed pieces (B) discharged from theexit port were post-treated in the same manner as in Example C toseparate and remove foreign matters. Foreign matters left in the crushedpieces were observed in the same manner as in Example C. Results areshown in Table 3 of FIG. 19.

[0204] III-[6] Example E (regarding the cleaning by the batch typecleaning device of a vertical type shown in FIG. 15)

[0205] This cleaning device had a vessel having an inner diameter of 400mm and a height of 500 mm, in which lattice type blades having an outerdiameter of 360 mm is provided at a center. The inner surface of thevessel and all surfaces of the lattice type blades were roughened tohave the irregularity of 200 to 300 μm deep.

[0206] The crushed pieces (A) of 22 kg and water of 20 kg wereintroduced into this cleaning device, and a height of the water leveladjustment pipe is regulated to the water level at this instant. Thecleaning operation was carried out for 20 minutes by rotating thelattice type blade at 300 rpm and supplying and draining water at a rateof 20 l/hr. After being cleaned, the cleaned crushed pieces (A) weretaken out therefrom by opening the piston-shaped discharge valve. Thecrushed pieces were post-treated in the same manner as in Example C toseparate and remove foreign matters. Foreign matters left in the crushedpieces were observed in the same manner as in Example C. Results areshown in Table 3 of FIG. 19.

[0207] III-[7] Comparative example F

[0208] The cleaning operation was carried out in the same manner as inExample E except that a crusher in which the inner surface of the vesseland surfaces of the agitator blades are not roughened. After beingcleaned, the cleaned crushed pieces (A) were taken out therefrom byopening the piston-shaped discharge valve. The crushed pieces werepost-treated in the same manner as in Example C to separate and removeforeign matters. Foreign matters left in the crushed pieces wereobserved in the same manner as in Example C. Results are shown in Table3 of FIG. 19.

[0209] It is apparent from Table 3 of FIG. 19 that there are extremelyless foreign matters in the crushed pieces after being cleaned byroughening part of the crusher to be in contact with the crushed pieces.Particularly there are none of foreign matters, of which the maximumlength exceeds 0.25 mm. On the other hand, it is also apparent that; inComparative example C, the operation of the crusher is impossible due tothe melting of crushed pieces; in Comparative examples D and F,particularly in D, a number of foreign matters are left in the treatedcrushed pieces; and in Comparative example E, the number of foreignmatters is uncountable because of a large amount of remnants derivedfrom coated film. In other words, Comparative examples are all extremelyinferior.

[0210] The present invention has been described in detail with respectto preferred embodiments, and it will now be apparent from the foregoingto those skilled in the art that changes and modifications may be madewithout departing from the invention in its broader aspects, and it isthe intention, therefore, in the appended claims to cover all suchchanges and modifications as fall within the true spirit of theinvention.

What is claimed is:
 1. A resin recycling system comprising: crushingmeans for individually crushing resin mold products into crushedresinous pieces in which 70% or more of the crushed resinous pieces havean equivalent diameter in a range from 1 to 50 mm; packing means forpacking the crushed resinous pieces of the respective mold product intoa bag having a transparent portion; classification means for irradiatinga light beam to the crushed resinous pieces in the bag through thetransparent portion, identifying a kind of the crushed resinous piecesbased on a reflected beam therefrom, and classifying the bags intorespective kinds of resins; and cleaning means for taking the crushedresinous pieces out from the bag and cleaning the crushed resinouspieces of the respective kind to remove foreign matters adhered on thesurface thereof.
 2. A resin recycling system as defined by claim 1,further comprising: recovery means for separating foreign matters from amixture of the crushed resinous pieces and the foreign matters, andrecovering the crushed resinous pieces.
 3. A resin recycling system asdefined by claim 1, wherein said cleaning means comprises a cleaningvessel and an agitating member provided in the cleaning vessel, and anabrasive surface for removing the foreign matters on the surface of thecrushed resinous pieces is provided on at least part of the inner wallof the cleaning vessel and/or the surface of the agitating member.
 4. Aresin recycling system as defined by claim 2, wherein said cleaningmeans comprises a cleaning vessel and an agitating member provided inthe cleaning vessel, and an abrasive surface for removing the foreignmatters on the surface of the crushed resinous pieces is provided on atleast part of the inner wall of the cleaning vessel and/or the surfaceof the agitating member.
 5. A resin recycling system as defined by claim1, further comprising: conveyor means for conveying the bag; and whereinsaid classification means comprises identification means, provided inthe vicinity of a predetermined identification position on a conveyingpath of said conveyor means, for irradiating a light beam to the crushedresinous pieces in the bag through the transparent portion of the bagpassing by the identification position and identifying the kind of thecrushed resinous pieces based on a reflected beam therefrom, and storagemeans for storing the identified kind of crushed resinous pieces and anexpected arrival time at which the bag of the crushed resinous pieceswould reach a predetermined classification position on the conveyingpath, while maintaining the correspondence between both the stored data,said classification means being disposed in the vicinity of saidpredetermined classification position, and operating to classify andcollect the respective bag as the crushed resinous pieces in the bagreaching the classification position is of the kind stored incorrespondence to the expected arrival time which is the same as thecurrent time.
 6. A crusher comprising: an endless conveyor for conveyingpolymer mold products, and an opposed member having an opposed surfaceconfronting at least one end of said endless conveyor on aconveying-directional side and disposed so that a distance between theopposed surface and a conveying surface of said endless conveyor becomessmaller in a conveying direction, wherein crushing edges or crushingpins are provided on at least one of the conveying surface of saidendless conveyor and the opposed surface of said opposed member, todirect toward the other, whereby the polymer mold products transportedby said endless conveyor are pushed into a gap between the conveyor andthe opposed member and crushed with said crushing edges or pins.
 7. Acrusher as defined by claim 6, wherein the crushing edges or pins areprovided on the conveying surface of said endless conveyer, and recessesor holes are provided on the opposed surface of said opposed member forallowing tip ends of the crushed edges or pins provided on said endlessconveyor to pass through the same.
 8. A crusher as defined by claim 6,wherein said opposed member comprises a second endless conveyor.
 9. Anidentification device for irradiating a light beam to a polymer productbeing conveyed by conveyor means, detecting the reflected beam or thedispersed beam from the polymer product by a sensor element, andidentifying a kind of the polymer product based on a detected result,wherein said sensor element is disposed at a predetermined position inthe vicinity of a conveying path of the polymer product, and a distancedetermination mechanism is disposed in said conveying means or in thevicinity thereof, for opposing the polymer product passing by saidsensor element to said sensor element at a predetermined distancebetween the both.
 10. An identification device as defined by claim 9,wherein said conveyor means comprises an endless conveyor and saidsensor element is disposed at a predetermined position beneath theconveying path constituted by said endless conveyor, and said distancedetermination mechanism comprises a light window provided at each ofportions of said endless conveyor passing over the predeterminedposition.
 11. An identification device as defined by claim 9, whereinthe conveyor means comprises an endless conveyor and said sensor elementis disposed at a predetermined position on a side of the conveying pathconstituted by said endless conveyor, and said distance determinationmechanism comprises a stopper member having a light window and disposedin front of said sensor element in the vicinity thereof and a guide forguiding the polymer product carried on said endless conveyor so that thepolymer product is pushed against the light window of the stopper memberto be able to pass by a front of said sensor element.
 12. A method forcleaning thermoplastic resinous products, comprising the steps of:crushing the collected thermoplastic resinous products into crushedpieces, supplying the crushed pieces together with water into a cleaningdevice having a vessel and a rotary body disposed in a rotatable mannerwithin the vessel, wherein at least part of the inner surface of thevessel and/or a surface of the rotary body is roughened, rotating therotary body and cleaning the crushed pieces.
 13. A method for cleaningthermoplastic resinous products as defined by claim 12, wherein theroughening is carried out so that the surface irregularity having adepth in a range from 40 to 2000 μm is provided on at least part of theinner surface of the vessel and/or the surface of the rotary body.
 14. Amethod for cleaning thermoplastic resinous products as defined by claim12, wherein water is continuously supplied from a plurality of portionsof the vessel and drained so that a water level in the cleaning deviceis maintained constant, while taking care to maintain a ratio in weightof the crushed pieces to the water constant.
 15. A method for cleaningthermoplastic resinous products as defined by claim 12, wherein thecleaning is carried out under the condition in that the ratio in weightof the crushed pieces to the water in the cleaning device is controlledto be 1:0.3 to 2.0; water is continuously supplied and drained so thatthe interior temperature of the cleaning device is 70° C. or lower; anda linear speed of a portion of the rotary body farthest from a rotaryshaft of the rotary body is in a range from 0.5 to 20 m/sec.
 16. Adevice for cleaning thermoplastic resinous products comprising a vesseland a rotary body built-in in the vessel, wherein the vessel has anentrance port for the thermoplastic resinous products provided in anupper area of one end thereof, an exit port for the thermoplasticresinous products provided in a lower area of the other end thereof, awater supply port and a drainage port; the drainage port being connectedto a drainage line for adjusting a water level; the rotary body having arotary shaft, a screw blade provided on the circumference of the rotaryshaft and at least one of a plurality of cleaning plates and cleaningpins; and at least part of the inner surface of the vessel and/orsurfaces of at least one of the cleaning plates and the cleaning pinsbeing roughened.
 17. A device for cleaning thermoplastic resinousproducts comprising a vessel and agitating blades, wherein the vesselhas an entrance port for crushed resinous pieces and a water supplyport, both provided in an upper portion thereof, and an exit port forthe crushed resinous pieces and a drainage port, both provided in alower portion provided thereof; a drainage line for adjusting a waterlevel being connected to the drainage port, and at least part of theinner surface of the vessel and/or surfaces of the agitating bladesbeing roughened.